偏心率对石蜡相变熔化过程影响的数值分析

Numerical Analysis of the Effect of Eccentricity on the Melting Process of Paraffin Phase Transformation

中文关键词: 相变蓄热  偏心率  传热强化  数值模拟

英文关键词: phase change thermal storage  eccentricity  heat transfer enhancement  the numerical simulation

中文摘要:

      数值模拟研究了内管和外管之间的圆心距离(偏心率)对石蜡在水平相变蓄热单元中熔化过程的影响。利用焓-多孔模型得到内管加热温度为60℃、65℃、70℃和偏心率为0.2、0.4、0.6、0.8、0.93工况下蓄热单元内的速度场,温度分布,液相率分布和综合传热系数。模拟研究结果表明,加热温度为65℃,偏心率为0.2、0.4、0.6、0.8、0.93,总熔化时间分别减少了31.6%、57.4%、76.4%、86.7%、86.7%,偏心率大于0.8,增大偏心率对减少熔化时间没有明显效果。加热温度为60℃,偏心率从0.8增加至0.933,Fo数增加了7.5%,总熔化时间增加。熔化过程中综合传热系数总体上逐渐减小。偏心率为0.6和0.8时,综合传热系数先增大后减小。熔化过程中,综合传热系数最大为329.72 J/(m2.K)。

英文摘要:

      The influence of center distance (eccentricity) between inner tube and outer tube on the melting process of paraffin in horizontal phase change thermal storage unit was investigated by numerical simulation. The enthalpy-porous model was employed to obtain the velocity field, temperature distribution, liquid phase rate distribution and comprehensive heat transfer coefficient in the inner tube heating temperature of 60℃, 65℃, 70℃ and eccentricity of 0.2, 0.4, 0.6, 0.8 and 0.93. The simulation results show that the heating temperature is 65℃, the eccentricity is 0.2, 0.4, 0.6, 0.8 and 0.93, and the total melting time is reduced by 31.6%, 57.4%, 76.4%, 86.7% and 86.7%, respectively. When the heating temperature is 60℃, the eccentricity increases from 0.8 to 0.933, the Fo number is increased by 7.5%, and the total melting time increases. The comprehensive heat transfer coefficient is decreased gradually in the melting process. When the eccentricity is 0.6 and 0.8, the comprehensive heat transfer coefficient first increases and then decreases. In the melting process, the maximum comprehensive heat transfer coefficient is 329.72 J/ (m2.K).